Share This

St. Louis, April 5, 2004 -- Scientists have known for years that abnormal activity involving a brain chemical called dopamine is somehow connected to the movements and vocalizations, or tics, associated with Tourette syndrome. Now neuroscience researchers at Washington University School of Medicine in St. Louis have found brain activity in these patients is abnormal during memory tasks, as well.

Related Articles

The researchers also found that giving Tourette syndrome patients the drug levodopa, which is used to treat abnormal dopamine activity in conditions such as Parkinson's disease, normalized brain activity during the memory tasks.

"We've observed in the living brain a dopamine-sensitive abnormality in people with tics. That's been hypothesized for 40 years, but this is the first time it's been demonstrated," says principal investigator Kevin J. Black, M.D., assistant professor of psychiatry, neurology and radiology and staff physician at Barnes-Jewish Hospital. "We actually have a direct demonstration of abnormal brain activation in people with Tourette syndrome that is corrected when they are given a dopamine-type medicine."

The study is published online and will appear in the May issue of the journal Biological Psychiatry.

Using functional magnetic resonance imaging (fMRI), the researchers compared eight adults with Tourette syndrome to 10 age- and gender-matched individuals without tics. Brain scans were taken while participants performed a memory task that involved remembering and identifying letters on a computer screen. The task measures working memory, a type of short-term memory that involves concentration on several things at once.

"We chose to look at the brain's response to a working memory task because past research has shown that working memory could be affected by dopamine levels in the brain," says first author Tamara Hershey, Ph.D., assistant professor of psychiatry and neurology at the School of Medicine. "We also know dopamine is involved in tics, but if we had studied a task that involved movement, for example, the fact that some tics involve movement could have made it harder to interpret the differences in brain activity."

In terms of speed and accuracy during the memory task, there were no differences between the two groups, but fMRI scans revealed that several brain areas were more active in Tourette syndrome patients than healthy participants.

The clearest differences were in a brain region called the parietal cortex, located at the top of the brain roughly in between the front and back of the head. Tourette syndrome patients also had increased activity in the medial frontal gyrus and in the thalamus -- which acts as the brain's relay station between the outer layer, or cortex and the rest of the nervous system.

"People with tics performed this task just as well as people without, so it's not something that involves a difference in output," Black says "Therefore, we believe any differences we saw in the fMRI scans reflect changes in the way the brain is working."

To determine whether the results were related to dopamine abnormalities, Hershey, Black and colleagues gave all participants an intravenous infusion of the drug levodopa.

When the two groups then repeated the original working memory task, brain activity in healthy participants was unchanged. In TS patients, however, the areas that had been abnormally overactive were substantially less active after treatment.

"Levodopa seems to normalize the excess activity we had seen in the parietal cortex in the group with tics," Hershey says. "There were changes in activity in the other structures, too, but the changes in the parietal cortex were the most dramatic."

Before decoding which brain scans belonged to which participants, Black looked at the patients' medical histories and used a standard method of rating the severity of their illness. He found that those with the most severe history of Tourette syndrome had the largest post-levodopa decreases in brain activity during the working memory task.

Now that they know the brain functions differently in people with Tourette syndrome, Black and Hershey plan to look at brain activity during different tasks to see whether they can find more dopamine-related differences.

Black also is finalizing a treatment study to determine if levodopa helps control tics in Tourette syndrome patients. That study should be completed later this year.

This research was supported by a Young Investigator award from the National Alliance for Research on Schizophrenia and Depression, by the Greater St. Louis Chapter of the American Parkinson's Disease Association (ADPA), the National Institutes of Health, the Parkinson's Disease Foundation, the Charles A. Dana Foundation and the ADPA Advanced Center for Parkinson's Disease Research at Washington University. The Tourette Syndrome Association provided recruitment support.

The full-time and volunteer faculty of Washington University School of Medicine are the physicians and surgeons of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked second in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

Washington University School Of Medicine. "Brain Activity, Including Memory-processing, Changes In Tourette Syndrome." ScienceDaily. ScienceDaily, 6 April 2004. <www.sciencedaily.com/releases/2004/04/040406083500.htm>.

Washington University School Of Medicine. (2004, April 6). Brain Activity, Including Memory-processing, Changes In Tourette Syndrome. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2004/04/040406083500.htm

Washington University School Of Medicine. "Brain Activity, Including Memory-processing, Changes In Tourette Syndrome." ScienceDaily. www.sciencedaily.com/releases/2004/04/040406083500.htm (accessed March 31, 2015).

More Mind & Brain News

Featured Research

Mar. 31, 2015 — During prenatal development, the brains of most animals, including humans, develop specifically male or female characteristics. But scientists have known little about the details of how this ... full story

Mar. 31, 2015 — A history of depression may put women at risk for developing diabetes during pregnancy, according to research. This study also pointed to how common depression is during pregnancy and the need for ... full story

Mar. 31, 2015 — Women who are abused by their partner or ex-partner are much less likely to use contraception; this exposes them to sexually transmitted diseases and leads to more frequent unintended pregnancies and ... full story

Mar. 31, 2015 — Video games not only sharpen the visual processing skills of frequent players, they might also improve the brain's ability to learn those skills, according to a new study. Gamers showed faster ... full story

Mar. 31, 2015 — Children who play video games for more than three hours a day are more likely to be hyperactive, get involved in fights and not be interested in school, says a new study. It examined the effects of ... full story

Mar. 31, 2015 — Differences in the way children and adults perceive the world extend to their sense of safety in their social and physical environments and this in turn can impact their health, say researchers. ... full story

Mar. 31, 2015 — Searching the Internet for information may make people feel smarter than they actually are, according to new research. In a series of experiments, participants who searched for information on the ... full story

Mar. 31, 2015 — In addition to their physical injuries, women who are victims of domestic violence are also at a greater risk of mental health problems such as depression and psychotic symptoms. "We studied the ... full story

Mar. 31, 2015 — A unique pattern of immune molecules in the cerebrospinal fluid of people with myalgic encephalomyelitis/chronic fatigue syndrome have been discovered, providing insights into the basis for cognitive ... full story

Mar. 31, 2015 — Children who get a taste of their parents' wine now and then may be more likely than their peers to start drinking by high school, according to a new report. The findings are based on 561 Rhode ... full story

Featured Videos

AAA: Distracted Driving a Serious Teen Problem

AP (Mar. 25, 2015) — While distracted driving is not a new problem for teens, new research from the AAA Foundation for Traffic Safety says it&apos;s much more serious than previously thought. (March 25)
Video provided by AP

Many Don't Know They Have Alzheimer's, But Their Doctors Do

Newsy (Mar. 24, 2015) — According to a new study by the Alzheimer&apos;s Association, more than half of those who have the degenerative brain disease aren&apos;t told by their doctors.
Video provided by Newsy

A Quick 45-Minute Nap Can Improve Your Memory

Newsy (Mar. 23, 2015) — Researchers found those who napped for 45 minutes to an hour before being tested on information recalled it five times better than those who didn&apos;t.
Video provided by Newsy

Dec. 17, 2012 — More than one in every ten schoolchildren suffers from a transient tic disorder, and 1% have a particular type of tic disorder known as Tourette syndrome. Researchers report on various modes of ... full story

Sep. 8, 2011 — Experts have confirmed it: Tics are not a rare or uncommon disorder. It is the second study to be conducted in Spain to date revealing that the prevalence of these motor disorders in the child ... full story

Apr. 14, 2011 — The use of cognitive-behavioral therapy to treat tics in Tourette syndrome may be as effective as and even superior to medication in certain cases. According to a new study, it was observed that ... full story

Mar. 24, 2011 — Contrary to intuition, people who suffer from the motor and vocal tics characteristic of Tourette syndrome actually perform behavioral tests of cognitive motor control more accurately and quickly ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.